• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.202-203
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• 2009

Plasma etching was studied to obtain high-efficiency Si solar cells. SiN nanoparticles were observed upon the plasma treatment using SF6 gas. The mechanism of the nanoparticles formation has been studied. A net increase in the current density (Jsc) of the cells of $1.7mA/cm^2$ and in the conversion efficiency ($\eta$) of 2.1% is obtained after the plasma treatment for 10s, thanks to the significant decrease of reflection in the shorter wavelength range.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.59-61
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• 2002

This research investigates electron beam to specification energy to Module that was generalized and schematized difference of curved line after existing V-I efficiency characteristic curve and irradiation. And will analyze cause of Si crystal Solar cell's efficiency addition and subtraction by 80keV electron beam investigation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.100-104
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• 2011

In this work, an optimum condition of electrolytes preparation for photovoltaic cells application was investigated experimentally in terms of impedance and conversion efficiency of the cells. 3-methoxyppropionitrie and redox pairs with LiI and $I_2$ were used as stable solvents for fabrication of electrolyte. Efficiency comparison of the prepared cells carried out for various additives and ionic liquids. From the results, there was an optimum concentration (about 0.3 M) of ionic liquids for efficient cell fabrication. For case of electrolyte using single DMAp additive, the maximum conversion efficiency of the cell was 6.4%($V_{oc}$: 0.78V, $J_{sc}$: 14.4 mA/$cm^2$, ff: 0.57). For case of electrolyte using both DMAp and CEMim additives, the maximum conversion efficiency of the cell was 7.2%($V_{oc}$: 0.79V, $J_{sc}$: 16 mA/$cm^2$, ff: 0.57). From the result of electrochemical impedance measurement, both Z1 and Z3 values of binary additives-based cell decreased compared to those of single additive-based. This is due to the decreased in internal and charge transfer resistivities of the cells.

• Korean Journal of Materials Research
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• v.22 no.5
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• pp.259-273
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• 2012

Chalcogenide-based semiconductors, such as $CuInSe_2$, $CuGaSe_2$, Cu(In,Ga)$Se_2$ (CIGS), and CdTe have attracted considerable interest as efficient materials in thin film solar cells (TFSCs). Currently, CIGS and CdTe TFSCs have demonstrated the highest power conversion efficiency (PCE) of over 11% in module production. However, commercialized CIGS and CdTe TFSCs have some limitations due to the scarcity of In, Ga, and Te and the environmental issues associated with Cd and Se. Recently, kesterite CZTS, which is one of the In- and Ga- free absorber materials, has been attracted considerable attention as a new candidate for use as an absorber material in thin film solar cells. The CZTS-based absorber material has outstanding characteristics such as band gap energy of 1.0 eV to 1.5 eV, high absorption coefficient on the order of $10^4cm^{-1}$, and high theoretical conversion efficiency of 32.2% in thin film solar cells. Despite these promising characteristics, research into CZTS-based thin film solar cells is still incomprehensive and related reports are quite few compared to those for CIGS thin film solar cells, which show high efficiency of over 20%. The recent development of kesterite-based CZTS thin film solar cells is summarized in this work. The new challenges for enhanced performance in CZTS thin films are examined and prospective issues are addressed as well.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.410.2-410.2
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• 2016

Tandem structure is promising in organic solar cells because of its double open-circuit voltage (VOC) and efficient photon energy conversion. In a typical tandem device, the two single sub-cells are stacked and connected by an interconnecting layer. The fabrication of two sub-cells are usually carried out in a glovebox filled with nitrogen or argon gas, which makes it expensive and laborious. We report a glovebox-free fabricated inverted tandem organic solar cells wherein the tandem structure comprises sandwiched interconnecting layer based on p-doped hole-transporting, metal, and electron-transporting materials. Complete fabrication process of the tandem device was performed outside the glove box. The tandem solar cells based on poly(3-hexylthiophene) (P3HT) and (6,6)-phenyl C61-butyric acid methyl ester (PCBM) can realize a high VOC, which sums up of the two sub-cells. The tandem device structure was ITO/ZnO/P3HT:PCBM/PEDOT:PSS/MoO3/Au/Al/ZnO-d/P3HT:PCBM/PEDOT:PSS/Ag. The separate sub-cells were morphologically and thermally stable up to 160 oC. The high stability of the active layer benefits in the fabrication processes of tandem device. The performance of tandem organic solar cells comes from the sub-cells with an 50 nm thick active layer of P3HT:PCBM, achieving an average power conversion efficiency (PCE) of 2.9% (n=12) with short-circuit current density (JSC) = 4.26 mA/cm2, VOC = 1.10 V, and fill factor (FF) = 0.62. Based on these findings, we propose a new method to improve the performance and stability of tandem organic solar cells.

• Journal of Industrial Technology
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• v.29 no.B
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• pp.145-149
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• 2009

A RF-DC converter is one of the most important components for a wireless power transmission. It has been developed for many applications such as space solar power system, and Radio Frequency Identification(RFID). In this paper, we designed three types of RF-DC converter and compare the performance of each. All types RF-DC convertoer have a maximum conversion efficiency at input power level of 0 dBm~5 dBm and RF-DC converter of third type was the best performance that has a 21.9% of conversion efficiency.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.316-316
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• 2010

Six metal-free organic dyes having thiophene (1), benzene-thiophene (2), thiophene-benzene (3), thiophene-pyridine(4), thiophene-thiophene (5), and pyridine (6) linkers between 9,9-dimethylfluorenyl terminal group and $\alpha$-cyanoacrylic acid anchor were synthesized. Among them, organic dye 5 showed the longest ${\lambda}}max$ value (424 nm) in UV-Vis absorption spectrum, better incident monochromatic photon-to-current conversion efficiency (IPCE), highest short circuit photocurrent density (JSC, 9.33 mA2/cm2), and highest overall conversion efficiency ($\eta$, 3.91%).

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.1.1-1.1
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• 2011

Electrospinning has known to be very effective tool for production of versatile one-dimensional (1D) nanostructured materials such as nanofibers, nanorod, and nanotubes and for easily assembly to two-, three-dimensional(2D, 3D) nanostructures such as thin film, membrane, and nonwoven web, etc. We have studied on the electrospinning technology for novel energy storage and conversion materials such as advanced separator, dye sensitized solar cell, supercapacitor, etc. High heat-resistive nanofibrous membrane as a new separator for future lithium ion polymer battery was prepared by electrospinning of PVdF based composite solution. The novel nanofibrous composite nonwovens have tensile strength of above 50 MPa and modulus of above 1.3 GPa. The internal structure of the electrospun composite nanofiber with a diameter of few hundreds nanometer were composed of core-shell nanostructure. And also electrospun $TiO_2$ nanorod/nanosphere based dye-sensitized solar cells with high efficiency are successfully prepared. Some battery performance will be introduced.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.36-36
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• 2010

Currently, there are several newly developed energy resources for the future to replace petroleum resources such as hydrogen fuel cell, solar cell, wind power, and etc. Among them, solar cell has attracted a worldwide concern, because it has an enormous amount of resources. In general, a study of solar cells can be classified in to an area of bulk type and thin-film type. Inorganic solar cells based on silicon have been tremendously developed in technology and efficiency. However, since there are many lithographic steps, high processing temperature approximately $1000^{\circ}C$, and expensive raw materials, a manufacturing cost of device are nearly reaching a limit. Contrary to those disadvantages, organic solar cells can be manufactured at room temperature. Also, it has many advantages such as a low cost, easy fabrication of thin film, and possible manufacture to a large size. Because it can be made to be flexible, research and development on solar cells are actively in progress for the next generation. ever though an efficiency of the organic solar cell is low compared to that of inorganic one, a continuous study is needed. In this paper, we report optimal device structure obtained by a program simulation for design and development of highly efficient organic photovoltaic cells. we have also compared simulated results to experimental ones.

• Journal of the Korean Vacuum Society
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• v.19 no.4
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• pp.314-318
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• 2010

We fabricated a plasma texturing for multi-crystalline silicon cells using reactive ion etching (RIE). Multi-crystalline Si cells have not benefited from the cost-effective wet-chemical texturing processes that reduce front surface reflectance on single-crystal wafers. Elimination of plasma damage has been achieved while keeping front reflectance to extremely low levels. We will discuss reflectance, quantum efficiency and conversion efficiency for multi-crystalline Si solar cell by each RIE process conditions.